Image sensors are electronic devices that respond to light and are also an assembly of light sensors composed of a large number of pixels, and function as the eyes of a human.
Image sensors are largely classified into a CCD (Charged Coupled Device) type and a CMOS (Complementary Metal Oxide Semiconductor) type.
The CMOS type can be achieved by a common process of manufacturing a semiconductor, such that manufacturing cost is low. Further, the CMOS type is suitable for long time use because the amounts of generated heat and consumed power are small, such that it is used for a video device of which the image quality is not so important, such as a CCTV.
In addition, the CCD type is advantageous in an environment with insufficient light, because it has a good color tone and a high sensitivity. Further, the CCD type currently has competitiveness in price, such that it has been used for small-sized digital cameras.
Further, image sensors with the CMOS type can be manufactured by stacking an image sensor and a driving circuit on one chip, using a common method of manufacturing a semiconductor.